Graphite holds an important position as an industrial material which has useful properties such as an excellent heat resistance, chemical resistance, high electric conductivity and so on, and has been used widely as materials for a secondary battery electrode, exothermic body, gasket, heat resistant seal and so on and a structural material.
Particularly, as for a graphite sheet obtained by heating a film of a given polymeric compound at and above 2400.degree. C. in the inert gas and, if necessary, rolling the resulting film, it is found that an uniform foaming state is made by heating at a high temperature and a graphite sheet having flexibility and elasticity is obtained by rolling. Moreover, this graphite sheet has a crystalline orientation in an surface extending direction of the graphite sheet (i.e. has a high orientation). Thus, a light material having a good heat resistance of which heat conductivity can not easily be affected by the thickness of the sheet can be provided (see Japanese Patent Laid-Open Publication No. Hei 3-75211 and 4-21508).
However, when the conventional flexible graphite is used for above-mentioned application, mechanical strength is sometimes insufficient due to its flexibility. On the other hand, a graphite sheet having a high orientation described in Japanese Patent Publication No. Hei 1-51442 is obtained by pressurizing and baking a film of a given polymeric compound and has good mechanical strength. However, since this graphite sheet does not have flexibility, a graphite element having an arbitrary shape can not be obtained, the application range is limited, and such a graphite sheet cannot be used in a wide range of applications.